Incarceration (inseparably adherent) can occur in any of the hernia; say the abdominal hernias- be it umbelical, ventral, inguinal or incisional hernia. The cause of incarceration is infection/ inflammation. So the structures from the skin to omemtum or bowel loops can get incarcerated through the hernial ring /site/defective area. (The defect is in the rectus shealth , allowing (from within) the abdominal contents to protrude through the opening in the rectus sheath/fascia upto the undersurface of the skin). Strangulated means the internal structures like,peritoneum, omentum or bowel /or all of these structures can get cought in the process and if left alone can go for gangrene.
Usually, we call incarcerarated /strangulated/ gangrenous in terms of peritoneum ,omemtum or the loops of small intestine which are prone for these processes-i e, the abdominal contents -any one of them or all of them.
All the three types (incarcerated, strangulated, or gangrenous) are" irreducible". Irreducible means the protruding herniated structures cannot be pushed back into the abdominal cavity even manually.( WHEN it goes in andcomes out ie, back and forth anytime of its own or on releasing the pressure of reduction, it is known as reducible). Irreducible can be incarcerated or strangulated or gangrenous.The difference the physician would be able to document, consolidating the findings.
Depending upon the structures involved in the process, the pathology(signs and symptoms ) shows up.